PubMed Health⌕ Search

Biomedical subjects

S P Marx

Publications and source records attributed to S P Marx.

4 recordsLinked to original sources
PubMed2001

A simple and efficient method for the purification of membrane-bound levansucrase from Zymomonas mobilis.

A new and efficient method for the purification of levansucrase from cell-free extracts of a flocculant mutant of Zymomonas mobilis ATCC 10988 was developed. Levansucrase activity was almost completely recovered and purified by a factor of 15 after precipitation with 0.1 m MnCl2 as a first capturing step. The enzyme was homogeneously purified by ultrafiltration and anion-exchange chromatography and exhibited a levan-forming activity of 39.2 U mg-1. The native enzyme formed large aggregates with an apparent molecular mass of more than 106 Da as determined by size-exclusion chromatography, whereas denaturing SDS-PAGE indicated an apparent molecular mass of 50 kDa for the subunits.

Cell Membrane↗
PubMed2000

Metabolization of beta-(2,6)-linked fructose-oligosaccharides by different bifidobacteria.

Low-molecular-mass beta-(2,6)-linked fructose-oligosaccharides (beta-(2,6)-FOS) were examined as a new carbohydrate source for growth of bifidobacteria. beta-(2,6)-FOS were prepared from microbial high-molecular-mass levan by acid hydrolysis and refined by cation-exchange chromatography. (13)C-NMR spectroscopy confirmed the presence of predominantly beta-(2,6)-fructosyl linkages in the oligosaccharides. More than 80% beta-(2,6)-FOS was recovered after in vitro incubation with amylolytic and proteolytic enzymes, implying resistance to degradation in the upper intestinal tract. Bifidobacterium adolescentis, B. longum, B. breve, and B. pseudocatenulatum were studied in vitro for their ability to metabolize beta-(2,6)-FOS. Growth, decrease in pH, formation of short- chain fatty acids (lactate, acetate, formate) and degradation of beta-(2,6)-FOS were markedly different among species. B. adolescentis showed the best growth, produced the highest amounts of organic acids and metabolized both short- and long-chain beta-(2, 6)-FOS.

Bifidobacterium↗
PubMed1999

Alpha-galactosidase of Bifidobacterium adolescentis DSM 20083.

Bifidobacterium adolescentis was grown anaerobically in medium enriched with alpha-D-galactosides. alpha-Galactosidase (EC 3.2.1. 22) was released from the cells by ultrasonic treatment and purified 36-fold by ultrafiltration, ammonium-sulphate precipitation, anion-exchange chromatography, and size-exclusion chromatography. Two protein bands were consistantly observed after sodium-dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Electrophoretically homogeneous alpha-galactosidase was only obtained by electroelution. The enzyme had an apparent molecular mass of 344 kDa and 79 kDa as judged by size-exclusion chromatography and SDS-PAGE, respectively. Activity-staining after nondenaturing SDS-PAGE indicated an apparent molecular mass of 145 kDa. Thus, a tetrameric structure of the protein is suggested. The alpha-galactosidase showed optimal activity at pH 5.5 and 55 degrees C. Lower pH values and higher temperatures rapidly inactivated alpha-galactosidase. The enzyme hydrolyzed specifically alpha-galactosidic linkages, and alpha-(1-3)-linkages were hydrolyzed at a higher rate compared to alpha-(1-6)-linkages. Hydrolysis of galactosides followed normal saturation kinetics; KM-values for p-nitrophenyl-alpha-galactopyranoside (p-NPG) and raffinose were calculated with 0.957 mM and 4.12 mM, respectively.

Bifidobacterium↗